In medical fields, radiation emission computed tomography (ECT: Emission Computed Tomography) apparatus is used that detects an annihilation radiation (for example, gamma rays) pair emitted from radiopharmaceutical that is administered to a subject and is localized to a site of interest for acquiring sectional images of the site of interest in the subject showing radiopharmaceutical distributions. Typical ECT equipment includes, for example, a PET (Positron Emission Tomography) device and an SPECT (Single Photon Emission Computed Tomography) device.
A PET device will be described by way of example. The PET device has a detector ring with block radiation detectors arranged in a ring shape. The detector ring is provided for surrounding a subject, and allows detection of radiation that is transmitted through the subject.
First, description will be given of a configuration of a conventional PET device. As shown in FIG. 10, a conventional PET device 50 includes a gantry 51 with an introducing hole that introduces a subject, a detector ring 53 having block radiation detectors 52 for detecting radiation being arranged inside the gantry 51 as to surround the introducing hole, and a support member 54 provided as to surround the detector ring 53. Each of the radiation detectors 52 has a bleeder unit 55 with a bleeder circuit. The bleeder unit 55 is provided between the support member 54 and the radiation detector 52 for connecting the support member 54 and the radiation detector 52. Such PET device is described, for example, in Patent Literature 1.
The PET device determines annihilation radiation pairs emitted from radiopharmaceutical. Specifically, an annihilation radiation pair emitted from inside of a subject M is a radiation pair having traveling directions opposite by 180 degrees.
[Patent Literature 1]
Japanese Patent Publication No. 2005-312930